Vehicle navigation apparatus providing rapid correction for excessive error in dead reckoning estimates of vehicle travel direction by direct application of position and direction information derived from gps position measurement data

Abstract

In a vehicle navigation apparatus having a control section which calculates relative vehicle positions and travel direction by dead reckoning calculations based on outputs from on-board sensors and periodically acquires GPS measurement data via a GPS receiver and applies error-reduction filter processing to these data to obtain position and travel direction information for correcting the calculated relative positions, the apparatus has a function for detecting that a travel direction obtained by dead reckoning contains an excessive error, and when that condition is detected, for directly applying an estimated vehicle position and travel direction derived directly from the GPS data, without filter processing, to correct the corresponding relative position and travel direction estimates. Rapid correction can thereby be achieved when the vehicle has been operated in a condition whereby a large amount of error has suddenly arisen in the travel direction that is estimated by the apparatus through dead reckoning calculation, e.g., after the vehicle has been rotated on a turntable with the vehicle navigation apparatus inoperative.